Enzootic equine cutaneous leishmaniasis in Venezuela

Detection of Leishmania spp. in Chronic Dermatitis: Retrospective Study in Exposed Horse Populations

Leishmania infantum is a protozoan causing human zoonotic visceral leishmaniasis (ZVL) and visceral–cutaneous canine leishmaniosis (CanL) in the Mediterranean Basin. L. infantum is able to infect a large number of wild and domestic species, including cats, dogs, and horses. Since the 1990s, clinical cases of equine leishmaniasis (EL), typically characterized by cutaneous forms, have been increasingly diagnosed worldwide. The aim of the present study was to evaluate the presence of clinical forms of EL in CanL-endemic areas in Italy, where exposure of equine populations was ascertained from recent serological surveys. For this purpose, formalin-fixed and paraffin-embedded skin biopsies of 47 horses presenting chronic dermatitis compatible with EL were retrospectively selected for the study and subjected to conventional and q-PCR. A singular positivity for L. infantum was found; BLAST analysis of sequence amplicons revealed a 99–100% homology with L. infantum sequences. The histological examination revealed a nodular lymphoplasmacytic and histiocytic infiltrate; immunohistochemistry showed rare macrophages containing numerous positive amastigotes. The present retrospective study reports, for the first time, a case of a cutaneous lesion by L. infantum occurring in an Italian horse. Pathological and healthy skin samples should be investigated on a larger scale to provide information on the potential clinical impact of EL in the practice, and to define the role of horses in epidemiological ZVL and CanL scenarios.

Equine infection with Leishmania spp. in Costa Rica: Study of five cases

BACKGROUND

Cutaneous forms of leishmaniosis due to Leishmania braziliensis have been reported in horses in the New World. Domestic animals play a role in the transmission of the disease. In Costa Rica, human cases of L. braziliensis, L. panamensis and L. infantum have been reported.

OBJECTIVES

The present report describes five cases of equine cutaneous leishmaniosis in Costa Rica. The aetiological diagnosis was based on the presence of the parasite within the lesions.

METHODS

Skin biopsies were used to perform histopathological analyses of the lesions. Immunohistochemistry was used to detect the presence of the Leishmania spp. antigens in tissue sections. Laser-capture micro-dissection and quantitative real-time PCR techniques were carried out to detect the pathogen nucleic acid within the microscopic lesions.

RESULTS

Histopathological analyses showed a granulomatous inflammation within the dermis, with multi-nucleated giant cells, macrophages, lymphocytes and few neutrophils and eosinophils. We detected the parasite by immunohistochemistry, using a rabbit polyclonal antibody raised against Leishmania spp. However, we could not identify Leishmania spp. by quantitative real-time PCR in formalin-fixed paraffin-embedded tissues, using specific primers for the conserved region in the minicircle of the Leishmania DNA kinetoplast.

CONCLUSIONS

Our results emphasise the importance of Leishmania spp. not only as a causative agent of equine cutaneous disease in the New World, but also as a possible emerging pathogen. Leishmaniosis is one of the most prevalent parasitic public health problems worldwide, and equines may have a role in the epidemiology of the disease.

Infection of the equine population by Leishmania parasites

Infection of equids by Leishmania (L.) parasites was previously described in both the Old and New World, particularly in Central and South America. Equine cutaneous leishmaniasis (CL) is caused by the Leishmania species, L. Viannia (V.) braziliensis and L. infantum, previously identified in humans and other parasite hosts living in the same geographic endemic areas. Sporadic autochthonous clinical cases, with no travel history, were documented in several countries including Germany, Portugal, Spain, Texas and Brazil; L. infantum and L. (Mundinia) martiniquensis were the infectious species. Prevalence of subclinical infections is extremely low and CL is observed in only a small proportion of infected animals with the appearance of single or multiple cutaneous lesions located on the head, external ear, scrotum, legs and the neck. To date, there has been no report of visceral abnormalities. However, the mild clinical profile of the disease and its spontaneous regression may indicate that skin lesions related to Leishmania infection is underdiagnosed. Importantly, although the prevalence of Leishmania infections in the equine population is low, a risk may rise from its potential involvement in the parasite transmission cycles as a source of infection for phlebotomine vectors and susceptible mammalian hosts. This review article summarises our current knowledge of the epidemiology, clinical presentation and diagnosis of Leishmania-infected equids.

Serological and Molecular Findings of Leishmania Infection in Healthy Donkeys (Equus asinus) from a Canine Leishmaniosis Endemic Focus in Tuscany, Italy: A Preliminary Report

Leishmania parasites are considered to be emergent zoonotic pathogens, which is a new concept regarding their epidemiology and the identification of novel animal hosts. The present study is the first in Italy to evaluate anti Leishmania seroprevalence, and the first in Europe to detect parasite DNA in donkeys' blood. The study was performed on jennies living in a Leishmania infantum endemic area of Central Italy. One hundred and ten blood samples were obtained from 67 healthy lactating Amiatina jennies that were semi-extensively reared in Tuscany. When possible, more than one sample was subsequently obtained from the same subject. All samples were processed by immunofluorescence antibody test (IFAT) and by polymerase chain reaction (PCR). For the results, 11 out of 30 animals (36.7%) showed positive scores under IFAT. In addition, 22 out of the other 37 jennies had positive scores, also. The animals showed titers ranging from 40 to 320. Furthermore, 2 subjects that were submitted for 2 and 3 blood samplings, both had more than one positive score. Moreover, 2 seropositive animals were positive for Leishmania DNA. Donkeys are considered to be a preferred source for a sandfly blood meal, even if clinical leishmaniosis has never been reported in Europe for this animal species. In the view of these facts, our preliminary findings would suggest the role of donkey as a potential reservoir for this protozoan agent. Additional studies would be welcome to elucidate the role of the donkey in Leishmania epidemiology of CanL endemic areas and to confirm the preliminary findings and the hypothesis proposed here.

Sources and sinks: revisiting the criteria for identifying reservoirs for American cutaneous leishmaniasis

Molecular-based approaches might be misleading for assessing the 'potential importance' of possible reservoirs for parasites unless used in conjunction with population dynamics and ecological studies that provide an understanding of the linkages between the enzootic transmission cycle (in wild animals) and that in domestic animals. Better understanding of ecological constraints on Leishmania transmission is needed to assess fully the passage of the parasite between its sandfly vector and different mammalian host species. We use a straightforward mathematical framework to illustrate that misuse of association patterns, as guidance for implementation of control measures, can in fact increase the endemism of leishmaniasis.

The current status of zoonotic leishmaniases and approaches to disease control

Leishmaniases are a complex of world-wide diseases with a range of clinical and epidemiological features caused by Leishmania spp. of protozoan parasites. Among 15 well-recognised Leishmania species known to infect humans, 13 have zoonotic nature, which include agents of visceral, cutaneous and mucocutaneous forms of the disease in both the Old and New Worlds. Currently, leishmaniases show a wider geographic distribution and increased global incidence of human disease than previously known. Environmental, demographic and human behavioural factors contribute to the changing landscape of leishmaniasis, which includes increasing risk factors for zoonotic cutaneous leishmaniases and new scenarios associated with the zoonotic visceral leishmaniases. The latter consist of the northward spread of Leishmania infantum transmission in Europe and America, the identification of unusual mammal hosts, and the decline of HIV-Leishmania co-infections in southern Europe following the introduction of the highly active antiretroviral therapy. Few advances have been made in the surveillance and control of the zoonotic leishmaniasis, however a number of tools have been developed for the control of the canine reservoir of L. infantum. These include: (i) several canine vaccine candidates, in particular an FML Leishmania enriched fraction showing good clinical protection, has been registered in Brazil for veterinary use; (ii) a number of insecticide-based preparations have been specifically registered for dog protection against sand fly bites. Laboratory and field studies have shown improved efficacy of these preparations for both individual and mass protection.

Inoculação experimental de Equus asinus com Leishmania chagasi Cunha & Chagas, 1937

Quatro Equus asinus foram inoculados com promastigotas de Leishmania chagasi Cunha & Chagas, 1937 e acompanhados durante 12 meses através de: pesquisa de amastigotas em esfregaços e culturas de sangue periférico em fragmentos de tecido do lábio inferior, medula óssea, baço e fígado e de testes de ELISA e TRALd. Estes foram positivos nos 8º, 10º e 12º meses após a inoculação. O exame histopatológico pós necropsia, demonstrou discreto número de amastigotas no fígado de dois dos eqüídeos inoculados. Apesar de desafiados com elevado número de promastigotas, os animais não desenvolveram infecções patentes e não infectaram experimentalmente a vetora Lutzomya longipalpis. Os resultados induzem a acreditar que os eqüídeos são desprovidos de importância como reservatórios na cadeia de transmissão da leishmaniose visceral, embora sirvam como boa fonte de alimentação sangüínea e proliferação da vetora Lutzomyia longipalpis.

Cutaneous leishmaniosis in a horse in southern Germany caused by Leishmania infantum

This report describes a case of cutaneous leishmaniosis in a horse in southern Germany. Diagnosis is based on histopathology, immunohistochemistry and electron microscopy. The protozoan was identified as Leishmania infantum via PCR and restriction fragment length polymorphism. The horse did not show specific Leishmania antibodies. The lesions healed completely within 6 months without any specific treatment. Since neither the infected horse nor its dam had ever left their rural area, autochthonous infection in Germany cannot be excluded. Factors possibly influencing the epidemiological situation are discussed.

Cotton rats (Sigmodon hispidus) and black rats (Rattus rattus) as possible reservoirs of Leishmania spp. in Lara State, Venezuela

A total of 519 wild animals belonging to eleven species were collected during a two year study in a cutaneous leishmaniasis endemic area in Venezuela (La Matica, Lara State). The animals were captured in home-made Tomahawk-like traps baited with maize, bananas or other available local fruits, and parasites were isolated from 27 specimens. Two different species were found naturally infected with flagellates, i.e., cotton rats (Sigmodon hispidus) and black rats (Rattus rattus). Characterization of the parasites using PCR, kDNA restriction pattern and hybridization with species-specific probes revealed the presence of Leishmania (L.) mexicana in three of the black rats and Leishmania (V.) braziliensis in two others. The latter species was also identified in the single positive specimen of S. hispidus. The results suggested both species of animals as possible reservoirs of Leishmania sp.

Cutaneous leishmaniasis in two horses

This report contains the clinical, histologic, immunohistochemical, and electron microscopic findings in two cases of equine cutaneous leishmaniasis. Nodular, sometimes crusty or ulcerated lesions were confined to the pinna and adjacent neck in both animals. The dermal inflammatory infiltrate was lymphohistiocytic in horse No. 1 and pyogranulomatous with formation of tuberculoid granulomas in horse No. 2. Numerous Leishmania organisms were found within macrophages in both animals. There was moderate to intense and specific reaction by immunoperoxidase using a polyclonal antiserum against Leishmania in both horses. Leishmania amastigotes were also revealed by electron microscopy. This is the first report of equine cutaneous leishmaniasis recognized in North America and Puerto Rico. Leishmaniasis should be considered in the differential diagnosis of cutaneous nodular diseases in the horse.

Cutaneous leishmaniasis in western Venezuela caused by infection with Leishmania venezuelensis and L. braziliensis variants

Between 1975 and 1987, epidemiological studies were carried out in several rural and urban communities in the central part of western Venezuela, especially in the state of Lara. 115 positive cultures were obtained from human cases and identified by their reactivity patterns to a cross-panel of specific monoclonal antibodies using a radioimmune binding assay; 53 were Leishmania venezuelensis and 62 were L. braziliensis. Most of these stocks were also characterized by isoenzyme electrophoresis, which confirmed the identification of the L. venezuelensis isolates. The enzyme electrophoretic profiles of the L. braziliensis isolates, however, revealed two populations with distinct electromorphs, one related to the World Health Organization L. braziliensis reference strain while the other population appeared to be a hybrid between L. braziliensis and L. guyanensis. L. braziliensis variants showed the widest geographical distribution, and were found in 7 states: Districto Federal (Caracas); Lara (Barquisimeto, Crespo, Iribarren, Jimenez, Morán, Palavecino, Torres, Urdaneta); Nueva Esparta (Margarita); Portuguesa (Las Cruces, Rio Amarillo); Trujillo (Cuicas); Yaracuy (Agua Fria, Cambural, Guaremal); and Zulia (Zipa-Yare). L. venezuelensis was found in the following endemic regions: Lara (Barquisimeto, Iribarren, Jimenez, Morán); Merida (Zéa); and Yaracuy (Campos Elias), showing that this parasite has a much wider geographical distribution than was initially recognized and that both these species can occur simultaneously within the same endemic region. Five isolates of L. braziliensis were made from infected donkeys (Equus asinus) in Urdaneta, Lara State, suggesting a possible domestic reservoir of L. braziliensis.

Leishmaniasis in a domestic goat in Kenya

The pathological and electron-microscopic features of the first case of autochthonous leishmaniasis affecting a domestic goat in Kenya are described. They are similar to what have been described in man and other animals. Using a short amino-acid sequence common to all the species of leishmania as primers for kDNA synthesis, the intervening sequence of 120 bases was amplified in the goat's tissues by polymerase chain reaction (PCR). The leishmania kinetoplast DNA sequence was detected in all the different infected tissues of the goat examined. The sensitivity and specificity of this assay are discussed. The result of the assay used was consistent with the parasite being either L. major or L. aethiopica as the infecting agent. The isoenzyme studies were consistent with L. aethiopica as the strain responsible for this goat's infection. The control of leishmaniasis and its vector must take into account the potential role of animal reservoirs in the environment. Even though Kenya and other East African countries are endemic for kala-azar, the presence of kala-azar in goats is of considerable veterinary public health importance in Africa. Efforts must not be spared to identify and detect other possible animal reservoirs in the subregion. Using DNA amplification techniques, which are sensitive and specific, such as the one described in this paper, sera and other biological fluids and tissues from different animal species should be utilized for detecting additional reservoirs for leishmania parasites particularly in known endemic areas of the world.

[Natural infection of Equus caballus by Leishmania sp--São Paulo, Brazil. (Brief scientific communication)]

E assinalado, pela primeira vez, o encontro de um cavalo (Equus caballus) infeclado por Leishmania sp, no Estado de São Paulo.

Diseases of the lips and oral cavity of domestic animals

Oral and lip lesions in domestic animals, as in man, may be due to a vast number of diseases. While some of these diseases are unique to each species, the majority of them are similar to human afflictions. These represent an untapped resource in comparative medicine, and research in this area can only benefit both man and the domestic animals he is dependent upon.

Conceitos de uma população local a respeito da leishmaniose mucocutânea em uma área endêmica

Uma investigação a respeito do que a população local pensa sobre vários aspectos da leishmaniose mucocutânea foi realizada em Três Braços, Bahia, uma área de alta prevalência de infecção por Leishmania braziliensis braziliensis. Os resultados obtidos indicam que essa população tem um entendimento razoavelmente bom sobre alguns aspectos epidemiológicos e tratamento dessa doença, mas demonstram seu pouco conhecimento concernente à etiologia e prevenção. Esses dados poderão ser valiosos, no futuro, em um planejamento do controle de transmissão da doença nesta comunidade.

The American leishmaniases: some observations on their ecology and epidemiology

As the first species of Leishmania encountered were the agents of human visceral and cutaneous leishmaniasis, it is understandable that studies on these parasites for a long time concentrated on those organisms commonly causing disease in man. Epidemiological studies over the past 20 years or so, however, have led to the inescapable conclusion that the genus Leishmania is comprised of numerous species of well adapted parasites, in a wide range of mammals, throughout most of those tropical and subtropical regions of the world where phlebotomine sandflies exist (Diptera: Psychodidae). Many of the leishmanias probably never gain entrance into man: due either to an incapacity to survive in his tissues, or (more likely) because the natural sandfly vectors do not feed on him. The leishmanias that do infect man are, nevertheless, among the greatest protozoological scourges of mankind, and a better understanding of their life-cycles may well help in future prevention or control of the diseases they cause. With few exceptions the leishmaniases are zoonoses, with a major source of infection in wild or domestic animals. In the Americas, the disease is essentially a rural one, and most commonly acquired by those penetrating forested or wooded regions. The following paper deals with the better known human leishmaniases of the New World, and some new ones, and discusses the major historical events in the laborious task of elucidating their ecology and epidemiology.